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Date:      Tue, 8 Aug 2017 10:49:56 +0000 (UTC)
From:      Andriy Gapon <avg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org
Subject:   svn commit: r322229 - vendor-sys/illumos/dist/uts/common/fs/zfs vendor-sys/illumos/dist/uts/common/fs/zfs/sys vendor/illumos/dist/lib/libzfs/common vendor/illumos/dist/lib/libzfs_core/common
Message-ID:  <201708081049.v78Anv3f030940@repo.freebsd.org>

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Author: avg
Date: Tue Aug  8 10:49:56 2017
New Revision: 322229
URL: https://svnweb.freebsd.org/changeset/base/322229

Log:
  7600 zfs rollback should pass target snapshot to kernel
  
  illumos/illumos-gate@77b171372ed21642e04c873ef1e87fe2365520df
  https://github.com/illumos/illumos-gate/commit/77b171372ed21642e04c873ef1e87fe2365520df
  
  https://www.illumos.org/issues/7600
    At present, the kernel side code seems to blindly rollback to whatever happens
    to be the latest snapshot at the time when the rollback task is processed.
    The expected target's name should be passed to the kernel driver and the sync
    task should validate that the target exists and that it is the latest snapshot
    indeed.
  
  Reviewed by: Matthew Ahrens <mahrens@delphix.com>
  Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
  Approved by: Robert Mustacchi <rm@joyent.com>
  Author: Andriy Gapon <avg@FreeBSD.org>

Modified:
  vendor/illumos/dist/lib/libzfs/common/libzfs_dataset.c
  vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.c
  vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.h

Changes in other areas also in this revision:
Modified:
  vendor-sys/illumos/dist/uts/common/fs/zfs/dsl_dataset.c
  vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dsl_dataset.h
  vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ioctl.c

Modified: vendor/illumos/dist/lib/libzfs/common/libzfs_dataset.c
==============================================================================
--- vendor/illumos/dist/lib/libzfs/common/libzfs_dataset.c	Tue Aug  8 10:48:52 2017	(r322228)
+++ vendor/illumos/dist/lib/libzfs/common/libzfs_dataset.c	Tue Aug  8 10:49:56 2017	(r322229)
@@ -3912,14 +3912,19 @@ zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, bo
 	}
 
 	/*
-	 * We rely on zfs_iter_children() to verify that there are no
-	 * newer snapshots for the given dataset.  Therefore, we can
-	 * simply pass the name on to the ioctl() call.  There is still
-	 * an unlikely race condition where the user has taken a
-	 * snapshot since we verified that this was the most recent.
+	 * Pass both the filesystem and the wanted snapshot names,
+	 * we would get an error back if the snapshot is destroyed or
+	 * a new snapshot is created before this request is processed.
 	 */
-	err = lzc_rollback(zhp->zfs_name, NULL, 0);
-	if (err != 0) {
+	err = lzc_rollback_to(zhp->zfs_name, snap->zfs_name);
+	if (err == EXDEV) {
+		zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
+		    "'%s' is not the latest snapshot"), snap->zfs_name);
+		(void) zfs_error_fmt(zhp->zfs_hdl, EZFS_BUSY,
+		    dgettext(TEXT_DOMAIN, "cannot rollback '%s'"),
+		    zhp->zfs_name);
+		return (err);
+	} else if (err != 0) {
 		(void) zfs_standard_error_fmt(zhp->zfs_hdl, errno,
 		    dgettext(TEXT_DOMAIN, "cannot rollback '%s'"),
 		    zhp->zfs_name);

Modified: vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.c
==============================================================================
--- vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.c	Tue Aug  8 10:48:52 2017	(r322228)
+++ vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.c	Tue Aug  8 10:49:56 2017	(r322229)
@@ -728,6 +728,9 @@ lzc_receive_with_header(const char *snapname, nvlist_t
  * Roll back this filesystem or volume to its most recent snapshot.
  * If snapnamebuf is not NULL, it will be filled in with the name
  * of the most recent snapshot.
+ * Note that the latest snapshot may change if a new one is concurrently
+ * created or the current one is destroyed.  lzc_rollback_to can be used
+ * to roll back to a specific latest snapshot.
  *
  * Return 0 on success or an errno on failure.
  */
@@ -747,6 +750,27 @@ lzc_rollback(const char *fsname, char *snapnamebuf, in
 	}
 	nvlist_free(result);
 
+	return (err);
+}
+
+/*
+ * Roll back this filesystem or volume to the specified snapshot,
+ * if possible.
+ *
+ * Return 0 on success or an errno on failure.
+ */
+int
+lzc_rollback_to(const char *fsname, const char *snapname)
+{
+	nvlist_t *args;
+	nvlist_t *result;
+	int err;
+
+	args = fnvlist_alloc();
+	fnvlist_add_string(args, "target", snapname);
+	err = lzc_ioctl(ZFS_IOC_ROLLBACK, fsname, args, &result);
+	nvlist_free(args);
+	nvlist_free(result);
 	return (err);
 }
 

Modified: vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.h
==============================================================================
--- vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.h	Tue Aug  8 10:48:52 2017	(r322228)
+++ vendor/illumos/dist/lib/libzfs_core/common/libzfs_core.h	Tue Aug  8 10:49:56 2017	(r322229)
@@ -84,6 +84,7 @@ int lzc_receive_with_header(const char *, nvlist_t *, 
 boolean_t lzc_exists(const char *);
 
 int lzc_rollback(const char *, char *, int);
+int lzc_rollback_to(const char *, const char *);
 
 #ifdef	__cplusplus
 }



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